Process of tawing and tanning.



till

sra rs rainarir time.

LOUIS E. LEVI, 0F MILVTAUKEE, "WISCONSIN, ASSIGNOR' 'IQ PFISTEE, & VOG-EL LEATHER COMPANY, OF MILWAUKEE, VISCONSIN, A. CORPORATION OF WISCONSIN.

PROCESS OF TAWING AND TANNING.

No Drawing.

To all whom it may concern:

Be it known that T, LOUIS E. LEVI, a citizen of the United States, and resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Processes of Tawing and Tanning, of which the following is a description.

It is a well known fact that compounds of chromium or other mineral salts have been used for the purpose of tawing or tanning hides and skins in order to convert the animal fiber into leather but the employment of such substances has been accompanied by certain disadvantages, namely :First, the leather is always soft; second, the process of tawing or tanning consumes too much time; third, the wearing quality of the leather is poor so that the life thereof is short; fourth, the cost of manufacture is too high.

The process hereinafter described has for its object to obviate the above mentioned disadvantages.

The hides and skins are prepared in the usual well known manner, that is, soaking, dehairing, washing, deliming, washing, pressing and pickling. The hides and skins are taken from the salt and sulfuric acid pickle or from the formaldehyde pickle, and pressed and placed in the drum or vat with or without the addition of salt NaCl) or glauber salt (Na SOQ with sufficient water to float the stock, in case drum tannage is used, or sufficient water to cover the stock in case vat tannage is used. Then, any of the following compounds are gradually added, or any combination of them, and the amount added in usual cases is from three to four per cent. of the pressed pickled weight of the stock. When the stock is struck through it is placed in a vat or drum with a solution of one of the following substances :Thiosulfate of soda, bisulfite of soda, bicarbonate of soda or carbonate of soda. Then it is washed, drained and finished in the usual manner. If the stock is intended for sole leather, to be hard and firm, it is simply oiled off on the grain and flesh. For softer upper leather the stock is impregnated with greases or fat liquors as this term is generally understood among tanners and curriers. The following are the compounds used by me in tawing or tanning hides or skins, either alone or in combina- Specification of Letters Patent.

Application filed December 29, 1913.

Patented Apr. T3, Militia.

Serial No. 809,221,

tion, in the presence or absence of an acid. In the manufacture of the compounds sodium or potassium salts are used:

Ferric chromate such as Basic ferric chromate such as Ferric sulfo chromates such as Fez 2Cl'O F6 9 i).+2k,o J 4 4 Fe CITO 2 0 2K s 6Fe'2 (S04) a+ zcrdjz 4) 4+ 2 4 3Fe (S0 OrO +3K and the like.

Basic ferric sulfo chromates such as Fe (S0,) -HZNaOH:

Fe (S0 2 (OH) -i-Na SO,

and the like which are excellent tanning or tawing compounds.

What I claim as new and desire to secure In testimony whereof, I aflix my signaby Letters Patent is: ture, in presence of tWo Witnesses.

1. The process of tanning consisting of immersing hides in a solution of a non-acid LOUIS E. LEVI.

5 ferric chromate.

2. The process of tanning consisting of Witnesses: immersing hides in a solution of a non-acid R. S. C. CALDWELL, substituted ferric chromate. KATHERINE HOLT.

Copies of this patent maybe obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

